EP0123359A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Electroacoustic transducer unit with reduced resonant frequency and mechanical spring with negative stiffness, preferably used in such a transducer unit
Assignee: Koninklijke Philips NV
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Filing: 1984-04-18
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Granted: —
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Expires: 2004-04-18
Abstract
Abstract An electroacoustic tranducer unit comprises an electroacoustic transducer including a diaphragm. This may be for example an electrodynamic transducer with a diaphragm (1), a magnet system (2) with an air gap (3), a voice-coil former (4) such a voice coil (5) arranged on this coil former in the air gap (3) of the magnet system (2). The transducer unit comprises means for reducing the resonant frequency of the transducer in the form of mechanical springs with negative spring stiffness (9 and 10), which springs are each coupled between a stationary part (11 or 8 respectively) of the transducer unit and movable part, for example the voice-coil former (4) or the diaphragm (1) of the transducer (Figure 1b). Further, the transducer unit comprises a control device (42) for correcting the position of the diaphragm (1) under the influence of a control signal (43) generated by the control device (Figure 4). The mechanical spring with negative spring stiffness comprises two blade springs of which both ends are coupled to each other and which, underthe influence of a compressive force F which acts in a direction along an imaginary line through both ends of the mechanical spring, are each bent in one or two opposite directions (Figures 2a en 2b). Such springs may also be employed for different purposes.
Inventors
- 👤 Kees Dijkstra
- 👤 Bernard Peter Videc
- 👤 Jan Huizinga
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 08:42
CPC Classifications
H; H04; H04R; H04R9/00; H04R9/06; H04R1/00; H04R1/42; H04R7/00; H04R7/26
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
111 words
An electroacoustic transducer unit comprising - an electroacoustic transducer with a diaphragm, and - means for reducing the resonant frequency of the electroacoustic transducer, which means comprise a mechanical spring with negative spring stiffness coupled between a movable part of the transducer and a stationary part of the transducer unit, characterized in that a mechanical spring is constructed by means of two blade springs of which both ends are coupled to each other and which, under the influence of a compressive force which acts on both ends of the mechanical spring in a direction along an imaginary line through said both ends, are each bent in one of two opposite directions.
Claim 2
Dependent Claim
111 words
An electroacoustic transducer unit comprising - an electroacoustic transducer with a diaphragm, and - means for reducing the resonant frequency of the electroacoustic transducer, which means comprise a mechanical spring with negative spring stiffness coupled between a movable part of the transducer and a stationary part of the transducer unit, characterized in that a mechanical spring is constructed by means of two blade springs of which both ends are coupled to each other and which, under the influence of a compressive force which acts on both ends of the mechanical spring in a direction along an imaginary line through said both ends, are each bent in one of two opposite directions.
Claim 3
Dependent Claim
51 words
An electroacoustic transducer unit as claimed in Claim 1, characterized in that at least one of the two facing major surfaces of the blade springs is provided with spacing means for keeping parts of the two blade springs spaced from each other in the case of large excursions of the diaphragm.
Claim 4
Dependent Claim
50 words
An electroacoustic transducer unit as claimed in Claim 1 or 2, characterized in that the centres of the two blade springs are also secured to each other, facing halves of the two blade springs each being bent in one of two opposite directions under the influence of the compressive force.
Claim 5
Dependent Claim
61 words
An electroacoustic transducer unit as claimed in Claim 1, 2 or 3, characterized in that the means for reducing the resonant frequency of the transducer comprise n mechanical springs with negative spring stiffness which are arranged at angles of 360° relative to each other or relative to a central axis of the transducer, where n≥2 but is preferably three or higher.
Claim 6
Dependent Claim
28 words
An electrcacoustic transducer unit as claimed in Claim 1, 2, 3 or 4, characterized in that the blade springs are provided with a layer of a damping material.
Claim 7
Dependent Claim
21 words
An electroacoustic transducer unit as claimed in Claim 5, characterized in that the layer of damping material functions as spacing means.
Claim 8
Dependent Claim
109 words
An electroacoustic transducer unit as claimed in any one of the preceding Claims, including an electroacoustic transducer in the form of an electrodynamic loudspeaker accommodated in an at least substantially air-tight enclosure, provided with a control device for correcting the average position of the diaphragm of the transducer in response to-i control signal to be generated by the control device, and detection means for detecting the average position of the diaphragm relative to its zero position and for supplying and output signal which is applied to the control device, characterized in that the control device is constructed to supply the control signal to a voice coil of the loudspeaker.
Claim 9
Dependent Claim
103 words
An electroacoustic transducer unit as claimed in any one of the Claim 1 to 6, including an electroacoustic transducer accommodated in an at least substantially air-tight enclosure, provided with a control device for correcting the average position of the diaphragm of the transducer in response to a control signal to be generated by the control device, and with detection means for detecting the average position of the diaphragm relative to its zero position and for supplying an output signal which is applied to the control device, characterized in that the detection means are constructed to determine the average air pressure in the enclosure.
Claim 10
Dependent Claim
141 words
A mechanical spring with negative spring stiffness, comprising a blade spring which under the influence of a compressive force which acts in a direction perpendicular to the direction of deflection of the blade spring is bent in a direction corresponding to said direction of deflection, in such a way that two halves of the blade spring are each bent one time, characterized in that the mechanical spring comprises a second blade spring, the ends and the centres of the two blade springs are coupled to each other, the second blade spring is bent under the influence of said compressive force in such a way that the two halves of the second blade spring are each bent one time in a direction corresponding to said direction of deflection, and facing halves of the two blade springs are each bent in opposite directions.
Claim 11
Dependent Claim
141 words
A mechanical spring with negative spring stiffness, comprising a blade spring which under the influence of a compressive force which acts in a direction perpendicular to the direction of deflection of the blade spring is bent in a direction corresponding to said direction of deflection, in such a way that two halves of the blade spring are each bent one time, characterized in that the mechanical spring comprises a second blade spring, the ends and the centres of the two blade springs are coupled to each other, the second blade spring is bent under the influence of said compressive force in such a way that the two halves of the second blade spring are each bent one time in a direction corresponding to said direction of deflection, and facing halves of the two blade springs are each bent in opposite directions.
Claim 12
Dependent Claim
56 words
A mechanical spring as claimed in Claim 9, characterized in that at least one of the two facing major surfaces of the blade springs is provided with spacing means for keeping parts of the two blade springs spaced from each other in the case of large deflection of the mechanical spring in said direction of deflection.
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